Ported burner

ABSTRACT

A fuel burner includes a tube extending along a centerline from a first end to a second end and having an outer surface and an inner surface defining a central passage. The central passage is supplied at the first end with a mixture of air and combustible fuel pre-mixed upstream of the tube. The second end is closed by an end wall in a fluid-tight manner. The tube has fluid directing structure for directing the pre-mixed mixture radially outward from the central passage to an exterior of the tube such that flames exiting adjacent fluid directing structures extend towards and impinge one another.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Appln. Ser. No.63/039,744, filed Jun. 16, 2020, the entirety of which is incorporatedby reference herein.

TECHNICAL FIELD

The invention relates to a fuel burner and, in particular, relates to acombustor for a heating appliance.

BACKGROUND

Power burners of various types have been in use for many years. “Nozzlemix” or “gun style” burners are those burners that inject fuel and airseparately in some manner so as to provide a stable flame without aported flame holder component. Other types of power burners use somemethod of pre-mixing the fuel and air and then delivering the fuel-airmixture to a ported burner “head”. These “heads” or “cans” can be madeof a variety of materials including perforated sheet metal, woven metalwire, woven ceramic fiber, etc. Flame stability, also referred to asflame retention, is key to making a burner that has a broad operatingrange and is capable of running at high primary aeration levels.

A broad operating range is desired for appliances that benefit frommodulation, in which the heat output varies depending on demand. Aburner having a flame that is lifted off the burner surface will remaincool, thereby prolonging its life. Lifting burners, however, can beunstable and can cause poor combustion (high CO) or loss of flamealtogether.

SUMMARY

In one example, a fuel burner includes a tube extending along acenterline from a first end to a second end and having an outer surfaceand an inner surface defining a central passage. The central passage issupplied at the first end with a mixture of air and combustible fuelpre-mixed upstream of the tube. The second end is closed by an end wallin a fluid-tight manner. The tube has fluid directing structure fordirecting the pre-mixed mixture radially outward from the centralpassage to an exterior of the tube such that flames exiting adjacentfluid directing structures extend towards and impinge one another.

In another example, a fuel burner includes a base extending along acenterline from a first end to a second end and having an upstream sideand a downstream side. The upstream side is supplied with a mixture ofair and combustible fuel pre-mixed upstream of the base. The base hasfluid directing structure for directing the pre-mixed mixture from theupstream side to the downstream side such that flames exiting adjacentfluid directing structures extend towards and impinge one another.

Other objects and advantages and a fuller understanding of the inventionwill be had from the following detailed description and the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an example fuel burner.

FIG. 2 is a section view of FIG. 1 taken along line 2-2.

FIG. 3 is a section view of FIG. 2 taken along line 3-3.

FIG. 4 is a top view of FIG. 3.

FIG. 5 is an enlarged view of another example fluid directing structure.

FIG. 6 is a schematic illustration of another example fuel burner.

DETAILED DESCRIPTION

The invention relates to a fuel burner and, in particular, relates to afuel burner for a heating appliance that includes ports and guides fordirecting fluid, e.g., fuel or a combination of air and fuel, about theexterior of the burner in a manner that lifts flames produced from theignited fluid above the burner surface. The burner surface can be planaror non-planar.

FIGS. 1-4 illustrate one example fuel burner 20 in accordance with thepresent invention. The fuel burner 20 may be used in industrial,household, and commercial appliances such as, for example, a waterheater, boiler, furnace, etc. In one instance, the fuel burner 20 can bea can-style burner. The fuel burner 20 includes a base or tube 40 thatextends along a centerline 42 from a first end 44 to a second end 46.The first end 44 includes a flange 45 for securing the burner 20 to, forexample, a portion of an appliance. Although the tube 40 is illustratedas having a circular shape, it will be appreciated that the tube mayexhibit alternative shapes, such as triangular, square, oval or anypolygonal shape.

The tube 40 has a constant cross-section. Alternatively, the tube 40 mayhave a cross-section that varies (not shown), e.g., is stepped, tapered,etc., along the centerline 42. In such a construction, the cross-sectionof the tube 40 may increase or decrease from the first end 44 to thesecond end 46 (not shown). In any case, the tube 40 is made from adurable, flame-resistant material, such as metal.

The tube 40 includes an outer surface 48 and an inner surface 50 thatdefines a central passage 60 extending through the tube from an opening62 at the first end 44 to an opening 64 at the second end 46. Theopening 64 at the second end 46 is sealed by an end wall 66 secured tothe tube 40 in a fluid-tight manner.

As shown in FIG. 2, the central passage 60 is configured to receive apre-mixed mixture of combustible fuel and air from a duct or passagewayin the appliance fluidly connected to a blower/gas valve premixingassembly (not shown). The combustible fuel can be a liquid, e.g.,atomized or vaporized, or gas.

The periphery of the tube 40 includes fluid directing structure 70 fordirecting fluid radially outward from the central passage 60 to aposition adjacent to and radially outward of the outer surface 48 andthe fluid directing structure, i.e., exterior to or outside of the tube.

The fluid directing structure 70 may include a series or openings withassociated fins or guides for directing the fluid in the desired manner(FIGS. 3-4). In one example, the fluid directing structure 70 includes aplurality of openings or ports 80 in the tube 40 for allowing theair/fuel mixture to pass from the central passage 60 to the exterior ofthe tube.

Each of the openings 80 extends entirely through the tube 40 from theouter surface 48 to the inner surface 50. Each opening 80 may have anyshape, such as rectangular, square, circular, triangular, etc. Theopenings 80 may all have the same shape or different shapes. Theopenings 80 are aligned with one another along the periphery, i.e.,around the circumference, of the tube 40 and can, in one example, forman endless loop. One or more endless loops of openings 80 may bepositioned adjacent to one another or spaced from one another along thelength of the tube 40. Each loop may have any number of openings 80. Theopenings 80 in adjacent loops may be aligned with one another or may becircumferentially offset from one another.

Alternatively or additionally, the openings 80 can be symmetrically orasymmetrically arranged about the circumference of the tube 40, arrangeddiametrically opposed from one another, arranged at predeterminedcircumferential positions from one another, arranged ordisproportionally concentrated on one half of the tube's length orcircumference or any combination of the foregoing.

The size, shape, configuration, and alignment of the openings 80 in thetube 40 is dictated by desired flow and performance characteristics ofthe air/fuel mixture flowing through the openings. Although the openings80 are illustrated as being arranged in a predetermined pattern alongthe tube 40, it will be appreciated that the openings may be randomlypositioned along the tube (not shown).

Each opening 80 includes a corresponding fluid directing projection orguide 82 for directing the air/fuel mixture passing through theassociated opening 80 radially outward and generally circumferentiallyabout the periphery of the tube 40, e.g., in a direction extending aboutthe centerline 42. The guides 82 are formed in or integrally attached tothe tube 40. In one example, the guides 82 are formed by lancing orlouvering the tube 40. Other methods of forming the guides 82 arecontemplated.

Each guide 80 can be substantially U- or V-shaped and includes a base 84connected to the tube 40. A pair of legs 86 extends in oppositedirections from the base 84 and generally circumferentially about thecenterline 42 (as shown). Each leg 86 extends at an angle (not shown)relative to the outer surface 48 the tube 40. The legs 86 may extend atthe same angle or at different angles relative to the outer surface 48.In any case, the legs 86 of adjacent guides 82 extend towards andthereby confront one another.

The openings 80 and corresponding guides 82 can be arranged such thatthe centerline 83 of each base 84 extends parallel to the centerline 42of the tube 40 (see FIG. 2). Alternatively or additionally, thecenterlines 83 can extend perpendicular to the centerline 42 (rotated90° from the configuration shown) and/or at angle(s) from the centerline42. In other words, the guides 82 can be arranged in any patternalong/about the tube 40 so long as legs 86 of adjacent guides 82confront one another. That said, the guides 82 can direct fluid passingtherethrough in upstream/downstream directions about and/or parallel tothe centerline 42 and/or in directions that are neither upstream nordownstream but about the centerline 42.

It will also be appreciated that the openings 80 and associated guides82 can be configured such that more than two guides confront oneanother. For example, one or more groups of three, four, five, etc.guides 82 can be arranged to direct fluid in a direction towards acommon point at the center of the arrangement (not shown).

The tube 40 can include additional or secondary fluid directingstructure 100, 102 constituting ports or openings at the respective ends42, 44 extending through the tube on opposite longitudinal sides of thefluid directing structure 70. In other words, the fluid directingstructure 70 is positioned longitudinally between the openings 100 inthe first end 42 and the openings 102 in the second end 44. The openings100 extend radially through the first end 42 and towards the centerline42 to the central passage 60. The openings 102 extend radially throughthe second end 44 and towards the centerline 42 to the central passage60. As shown in FIG. 3, neither the openings 100 nor the openings 102includes associated fins or guides. The openings 100, 102 can becircular (as shown), round, rectangular, polygonal, etc. Either or bothsets of openings 100, 102 can be omitted.

In an alternative configuration shown in FIG. 5, the openings 100, 102are designated as 100 a, 102 a for clarity. At least a portion of theopenings 100 a can include an associated guide 110 extending from orsecured to the tube 40 and configured to direct fluid towards the secondend 44. Alternatively or additionally, at least a portion of theopenings 102 a can include an associated guide (not shown) extendingfrom or secured to the tube 40 and configured to direct fluid towardsthe first end 42. In this manner, the guides can direct fluid generallytowards one another on opposite sides of the fluid directing structure70. The guides and openings 100 a, 102 a can be formed from louvering orlancing the tube 40.

In this configuration, the openings 100 a, 102 a can have a generallyrectangular shape. The associated guides can extend at the same anglerelative to the outer surface 48 as the guides 82 or at a differentangle. The openings 100 a, 102 a and associated guides can becircumferentially offset from the openings 60 and guides 82 (as shown)or aligned therewith.

In operation, the pre-mixed mixture M flows into the central passage 60at the first end 44 of the tube 40 (see FIG. 2). The end wall 66prevents the pre-mixed mixture M from exiting the second end 46 of thetube 40 except through the fluid directing structures 70, 100, 102.Consequently, the pre-mixed mixture M is directed radially outwardthrough the fluid directing structures 70, 100, 102 in the respectivemanners R₁, R₂, R₃ to the tube exterior.

Since the circumferentially adjacent guides 82 confront one another,fluid exiting the guides flows in a direction towards the adjacent guidesuch that the resulting flames F₁ impinge one another as shown in FIG.3. This advantageously lifts the impinging flames F₁ off the outersurface 48 of the burner and provides enhanced flame stability. At thesame time, the pre-mixed mixture M also flows through the openings 100,102 to the exterior of the tube 40 such that the resulting flames (notshown) extend substantially normal to the outer surface 48.

In the case of the openings 100 a, 102 a and any guides associatedtherewith (FIG. 5), the pre-mixed mixtures flowing through the openings100 a, 102 a are directed towards one another such that the resultingflames F₂ extend towards one another and towards the flames F₁ extendingfrom the guides 82. Both configurations for the secondary fluiddirecting structure help to provide flame stability at the ends 42, 44of the tube 40.

In any case, to produce the flames the pre-mixed mixture is ignited byan ignition device (not shown) of any number of types well known in theart and positioned in any number of suitable locations to light theburner 20. Flame proving means (not shown) can be positioned in anynumber of suitable locations to detect the presence of flame. The flamesfrom the ignited air/fuel mixture is directed into, for example, theheat exchange tube of the heating appliance.

In another example shown in FIG. 6, the fuel burner 220 has a planarbase 240. The base 240 extends along a centerline 242 from a first end244 to a second end 246. The base 240 has a first surface or side 248and a second surface or side 250. The pre-mixed mixture M is suppliedfrom the second surface 250 side of the base 240 and, thus, the secondsurface is the upstream side or surface of the base.

The fluid directing structure 70 is identical to the fluid directingstructure shown and described in FIGS. 1-5 except the associated guides82 and openings 80 in FIG. 6 are provided on planar surfaces 248, 250instead of curved surfaces 48, 50. That said, the fluid directingstructure 70 of the fuel burner 220 can direct fluid passingtherethrough perpendicular to the centerline 242 (as shown), parallel tothe centerline 242 and/or one or more angles relative to the centerline242 (not shown). In all cases, the legs 82 of adjacent fluid directingstructures 70 of the fuel burner 220 confront one another and, thus, theflames exiting therefrom impinge one another and are lifted off thesurface 248.

Due to the exceptional flame retention/stability of the burner of thepresent invention, it is capable of running at very high combustionloadings. High loadings allow the burner to run in a stable “liftedflame” mode i.e., the flame is spaced from the burner surfaces. Liftingof the flame in this manner is desirable in that the burner surfaces arenot directly heated, thereby maintaining the surfaces at a lowertemperature and lengthening the usable life of the combustor. A highcombustion loading also allows the use of a smaller, space saving, andless costly burner for a given application. Furthermore, the burner ofthe present invention, due to the exceptional flame retention asdiscussed above, is also capable of operating cleanly (low CO) at veryhigh levels of excess air, which produces NOx levels well below thoseachievable with conventional burner.

The preferred embodiments of the invention have been illustrated anddescribed in detail. However, the present invention is not to beconsidered limited to the precise construction disclosed. For example,it will be understood that the burner described above can incorporate a“variable port area” by configuring the end wall 66 to be movable alongthe centerline 42 of the tube 40. The wall 66 can be movable to preventfluid flow through, for example, the openings 102. Such a constructionwould allow for optimized combustion performance by matching the portarea for combustion to the power output required.

What have been described above are examples of the present invention. Itis, of course, not possible to describe every conceivable combination ofcomponents or methodologies for purposes of describing the presentinvention, but one of ordinary skill in the art will recognize that manyfurther combinations and permutations of the present invention arepossible. Accordingly, the present invention is intended to embrace allsuch alterations, modifications and variations that fall within thespirit and scope of the appended claims.

What is claimed is:
 1. A fuel burner comprising: a tube extending alonga centerline from a first end to a second end and having an outersurface and an inner surface defining a central passage, the centralpassage being supplied at the first end with a mixture of air andcombustible fuel pre-mixed upstream of the tube, the second end beingclosed by an end wall in a fluid-tight manner, the tube having fluiddirecting structure for directing the pre-mixed mixture radially outwardfrom the central passage to an exterior of the tube such that flamesexiting adjacent fluid directing structures extend towards and impingeone another.
 2. The fuel burner of claim 1, wherein the fluid directingstructure includes a plurality of openings and a guide associated witheach opening, each guide including a base connected to the tube and apair of legs extending circumferentially in opposite directions from thebase such that the legs of adjacent fluid directing structures confrontone another.
 3. The fuel burner of claim 2, wherein the guides arearranged in a series of rows that extend continuously around theperiphery of the tube to encircle the centerline.
 4. The fuel burner ofclaim 2, wherein the guides are substantially V-shaped.
 5. The fuelburner of claim 1, further comprising secondary fluid directingstructure positioned on opposite longitudinal sides of the fluiddirecting structure.
 6. The fuel burner of claim 5, wherein thesecondary fluid directing structure comprises ports extending throughthe tube to the central passage.
 7. The fuel burner of claim 6, whereina guide is associated with each port and extends towards the fluiddirecting structure.
 8. A heating appliance including the fuel burner ofclaim
 1. 9. A fuel burner comprising: a base extending along acenterline from a first end to a second end and having an upstream sideand a downstream side, the upstream side being supplied with a mixtureof air and combustible fuel pre-mixed upstream of the base, the basehaving fluid directing structure for directing the pre-mixed mixturefrom the upstream side to the downstream side such that flames exitingadjacent fluid directing structures extend towards and impinge oneanother.
 10. The fuel burner of claim 9, wherein the fluid directingstructure includes a plurality of openings and a guide associated witheach opening, each guide including a base connected to the tube and apair of legs extending in opposite directions from the base such thatthe legs of adjacent fluid directing structures confront one another.11. The fuel burner of claim 10, wherein the guides are substantiallyV-shaped.
 12. The fuel burner of claim 9, further comprising secondaryfluid directing structure positioned on opposite longitudinal sides ofthe fluid directing structure.
 13. The fuel burner of claim 12, whereinthe secondary fluid directing structure comprises ports extendingthrough the base.
 14. The fuel burner of claim 13, wherein a guide isassociated with each port and extends towards the fluid directingstructure.
 15. A heating appliance including the fuel burner of claim 9.